ltt/branches/poly/lttv/main/module.c

   1
   2 /* This file is part of the Linux Trace Toolkit viewer
   3  * Copyright (C) 2003-2004 Michel Dagenais
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License Version 2 as
   7  * published by the Free Software Foundation;
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  17  * MA 02111-1307, USA.
  18  */
  19
  20
  21 /* module.c : Implementation of the module loading/unloading mechanism. */
  22
  23 #include <lttv/module.h>
  24 #include <gmodule.h>
  25
  26
  27 struct _LttvLibrary
  28 {
  29   LttvLibraryInfo info;
  30   GPtrArray *modules;
  31   GModule *gm;
  32   guint locked_loaded;
  33 };
  34
  35
  36 struct _LttvModule
  37 {
  38   LttvModuleInfo info;
  39   char **prerequisites_names;
  40   GPtrArray *prerequisites;
  41 };
  42
  43
  44 /* Modules are searched by name. However, a library may be loaded which
  45    provides a module with the same name as an existing one. A stack of
  46    modules is thus maintained for each name.
  47
  48    Libraries correspond to glib modules. The g_module function is
  49    responsible for loading each library only once. */
  50
  51 static GHashTable *modules_by_name = NULL;
  52
  53 static GPtrArray *libraries = NULL;
  54
  55 static GHashTable *libraries_by_g_module = NULL;
  56
  57 static GPtrArray *library_paths = NULL;
  58
  59 static gboolean initialized = FALSE;
  60
  61 static gboolean destroyed = TRUE;
  62
  63 static struct _LttvModuleDescription *builtin_chain = NULL;
  64
  65 static struct _LttvModuleDescription *module_chain = NULL;
  66
  67 static struct _LttvModuleDescription **module_next = &module_chain;
  68
  69 static GQuark lttv_module_error;
  70
  71 static void init();
  72
  73 static finish_destroy();
  74
  75 static void module_release(LttvModule *m);
  76
  77
  78 static LttvLibrary *library_add(char *name, char *path, GModule *gm)
  79 {
  80   LttvLibrary *l;
  81
  82   LttvModule *m;
  83
  84   struct _LttvModuleDescription *link;
  85
  86   GPtrArray *modules;
  87
  88   l = g_new(LttvLibrary, 1);
  89   l->modules = g_ptr_array_new();
  90   l->gm = gm;
  91   l->locked_loaded = 0;
  92   l->info.name = g_strdup(name);
  93   l->info.path = g_strdup(path);
  94   l->info.load_count = 0;
  95
  96   g_ptr_array_add(libraries, l);
  97   g_hash_table_insert(libraries_by_g_module, gm, l);
  98
  99   *module_next = NULL;
 100   for(link = module_chain; link != NULL; link = link->next) {
 101     m = g_new(LttvModule, 1);
 102     g_ptr_array_add(l->modules, m);
 103
 104     modules = g_hash_table_lookup(modules_by_name, link->name);
 105     if(modules == NULL) {
 106       modules = g_ptr_array_new();
 107       g_hash_table_insert(modules_by_name, g_strdup(link->name), modules);
 108     }
 109     g_ptr_array_add(modules, m);
 110
 111     m->prerequisites_names = link->prerequisites;
 112     m->prerequisites = g_ptr_array_new();
 113     m->info.name = link->name;
 114     m->info.short_description = link->short_description;
 115     m->info.description = link->description;
 116     m->info.init = link->init;
 117     m->info.destroy = link->destroy;
 118     m->info.library = l;
 119     m->info.require_count = 0;
 120     m->info.use_count = 0;
 121     m->info.prerequisites_number = link->prerequisites_number;
 122   }
 123   return l;
 124 }
 125
 126
 127 static void library_remove(LttvLibrary *l)
 128 {
 129   LttvModule *m;
 130
 131   GPtrArray *modules;
 132
 133   guint i;
 134
 135   char *key;
 136
 137   for(i = 0 ; i < l->modules->len ; i++) {
 138     m = (LttvModule *)(l->modules->pdata[i]);
 139
 140     g_hash_table_lookup_extended(modules_by_name, m->info.name,
 141                                  (gpointer *)&key, (gpointer *)&modules);
 142     g_assert(modules != NULL);
 143     g_ptr_array_remove(modules, m);
 144     if(modules->len == 0) {
 145       g_hash_table_remove(modules_by_name, m->info.name);
 146       g_ptr_array_free(modules, TRUE);
 147       g_free(key);
 148     }
 149
 150     g_ptr_array_free(m->prerequisites, TRUE);
 151     g_free(m);
 152   }
 153
 154   g_ptr_array_remove(libraries, l);
 155   g_hash_table_remove(libraries_by_g_module, l->gm);
 156   g_ptr_array_free(l->modules, TRUE);
 157   g_free(l->info.name);
 158   g_free(l->info.path);
 159   g_free(l);
 160 }
 161
 162
 163 static LttvLibrary *library_load(char *name, GError **error)
 164 {
 165   GModule *gm;
 166
 167   int i, nb;
 168
 169   char *path, *pathname;
 170
 171   LttvLibrary *l;
 172
 173   GString *messages = g_string_new("");
 174
 175   /* insure that module.c is initialized */
 176
 177   init();
 178
 179   /* Try to find the library along all the user specified paths */
 180
 181   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Load library %s", name);
 182   nb = lttv_library_path_number();
 183   for(i = 0 ; i <= nb ; i++) {
 184     if(i < nb) path = lttv_library_path_get(i);
 185     else path = NULL;
 186
 187     pathname = g_module_build_path(path ,name);
 188     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Try path %s", pathname);
 189     module_chain = NULL;
 190     module_next = &module_chain;
 191     gm = g_module_open(pathname,0);
 192     g_free(pathname);
 193
 194     if(gm != NULL) break;
 195
 196     g_string_append(messages, g_module_error());
 197     g_string_append(messages, "\n");
 198     g_log(G_LOG_DOMAIN,G_LOG_LEVEL_INFO,"Trial failed, %s", g_module_error());
 199   }
 200
 201   /* Module cannot be found */
 202
 203   if(gm == NULL) {
 204     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Failed to load %s", name);
 205     g_set_error(error, lttv_module_error, LTTV_MODULE_NOT_FOUND,
 206           "Cannot load library %s: %s", name, messages->str);
 207     g_string_free(messages, TRUE);
 208     return NULL;
 209   }
 210   g_string_free(messages, TRUE);
 211
 212   /* Check if the library was already loaded */
 213
 214   l = g_hash_table_lookup(libraries_by_g_module, gm);
 215
 216   /* This library was not already loaded */
 217
 218   if(l == NULL) {
 219     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Library %s (%s) loaded", name,
 220         g_module_name(gm));
 221     l = library_add(name, path, gm);
 222   }
 223   return l;
 224 }
 225
 226
 227 LttvLibrary *lttv_library_load(char *name, GError **error)
 228 {
 229   LttvLibrary *l = library_load(name, error);
 230   l->info.load_count++;
 231   return l;
 232 }
 233
 234
 235 static void library_unload(LttvLibrary *l)
 236 {
 237   guint i, len;
 238
 239   GModule *gm;
 240
 241   LttvModule *m;
 242
 243   if(l->locked_loaded > 0) {
 244     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Unload library %s: locked loaded",
 245         l->info.name);
 246     return;
 247   }
 248
 249   if(l->info.load_count > 0) {
 250     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Unload library %s: load count %d",
 251         l->info.name, l->info.load_count);
 252     return;
 253   }
 254
 255   /* Check if all its modules have been released */
 256
 257   for(i = 0 ; i < l->modules->len ; i++) {
 258     m = (LttvModule *)(l->modules->pdata[i]);
 259     if(m->info.use_count > 0) {
 260       g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO,"Unload library %s: module %s used",
 261            l->info.name, m->info.name);
 262       return;
 263     }
 264   }
 265
 266   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Unload library %s: close the GModule",
 267        l->info.name);
 268   gm = l->gm;
 269   library_remove(l);
 270   if(gm != NULL) g_module_close(gm);
 271
 272   /* insure that module.c will be finalized */
 273
 274   finish_destroy();
 275 }
 276
 277
 278 void lttv_library_unload(LttvLibrary *l)
 279 {
 280   l->info.load_count--;
 281   library_unload(l);
 282 }
 283
 284
 285 static void library_lock_loaded(LttvLibrary *l)
 286 {
 287   l->locked_loaded++;
 288 }
 289
 290
 291 static void library_unlock_loaded(LttvLibrary *l)
 292 {
 293   l->locked_loaded--;
 294   library_unload(l);
 295 }
 296
 297
 298 static LttvModule *module_require(char *name, GError **error)
 299 {
 300   GError *tmp_error = NULL;
 301
 302   guint i, j;
 303
 304   LttvModule *m, *required;
 305
 306   LttvLibrary *l = NULL;
 307
 308   GPtrArray *modules;
 309
 310   /* Insure that module.c is initialized */
 311
 312   init();
 313
 314   /* Check if the module is already loaded */
 315
 316   modules = g_hash_table_lookup(modules_by_name, name);
 317
 318   /* Try to load a library having the module name */
 319
 320   if(modules == NULL) {
 321     l = library_load(name, error);
 322     if(l == NULL) return NULL;
 323     else library_lock_loaded(l);
 324
 325     /* A library was found, does it contain the named module */
 326
 327     modules = g_hash_table_lookup(modules_by_name, name);
 328     if(modules == NULL) {
 329       g_set_error(error, lttv_module_error, LTTV_MODULE_NOT_FOUND,
 330           "Module %s not found in library %s", name, l->info.name);
 331       library_unlock_loaded(l);
 332       return NULL;
 333     }
 334   }
 335   m = (LttvModule *)(modules->pdata[modules->len - 1]);
 336
 337   /* We have the module */
 338
 339   m->info.use_count++;
 340
 341   /* First use of the module. Initialize after getting the prerequisites */
 342
 343   if(m->info.use_count == 1) {
 344     for(i = 0 ; i < m->info.prerequisites_number ; i++) {
 345       required = module_require(m->prerequisites_names[i], &tmp_error);
 346
 347       /* A prerequisite could not be found, undo everything and fail */
 348
 349       if(required == NULL) {
 350         for(j = 0 ; j < m->prerequisites->len ; j++) {
 351           module_release((LttvModule *)(m->prerequisites->pdata[j]));
 352         }
 353         g_ptr_array_set_size(m->prerequisites, 0);
 354         if(l != NULL) library_unlock_loaded(l);
 355         g_set_error(error, lttv_module_error, LTTV_MODULE_NOT_FOUND,
 356             "Cannot find prerequisite for module %s: %s", name,
 357             tmp_error->message);
 358         g_clear_error(&tmp_error);
 359         return NULL;
 360       }
 361       g_ptr_array_add(m->prerequisites, required);
 362     }
 363     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Module %s: init()", m->info.name);
 364     m->info.init();
 365   }
 366
 367   /* Decrement the load count of the library. It will not really be
 368      unloaded since it contains a currently used module. */
 369
 370   if(l != NULL) library_unlock_loaded(l);
 371
 372   return(m);
 373 }
 374
 375
 376 /* The require_count for a module is the number of explicit calls to
 377    lttv_module_require, while the use_count also counts the number of times
 378    a module is needed as a prerequisite. */
 379
 380 LttvModule *lttv_module_require(char *name, GError **error)
 381 {
 382   LttvModule *m = module_require(name, error);
 383   if(m != NULL) m->info.require_count++;
 384   return(m);
 385 }
 386
 387
 388 static void module_release(LttvModule *m)
 389 {
 390   guint i;
 391
 392   library_lock_loaded(m->info.library);
 393
 394   m->info.use_count--;
 395   if(m->info.use_count == 0) {
 396     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Module %s: destroy()",m->info.name);
 397     m->info.destroy();
 398     for(i = 0 ; i < m->prerequisites->len ; i++) {
 399       module_release((LttvModule *)(m->prerequisites->pdata[i]));
 400     }
 401     g_ptr_array_set_size(m->prerequisites, 0);
 402   }
 403   library_unlock_loaded(m->info.library);
 404 }
 405
 406
 407 void lttv_module_release(LttvModule *m)
 408 {
 409   m->info.require_count--;
 410   module_release(m);
 411 }
 412
 413
 414 void lttv_module_info(LttvModule *m, LttvModuleInfo *info)
 415 {
 416   *info = m->info;
 417 }
 418
 419
 420 unsigned lttv_module_prerequisite_number(LttvModule *m)
 421 {
 422   return m->prerequisites->len;
 423 }
 424
 425
 426 LttvModule *lttv_module_prerequisite_get(LttvModule *m, unsigned i)
 427 {
 428   return (LttvModule *)(m->prerequisites->pdata[i]);
 429 }
 430
 431
 432 void lttv_library_info(LttvLibrary *l, LttvLibraryInfo *info)
 433 {
 434   *info = l->info;
 435 }
 436
 437
 438 unsigned lttv_library_module_number(LttvLibrary *l)
 439 {
 440   return l->modules->len;
 441 }
 442
 443
 444 LttvModule *lttv_library_module_get(LttvLibrary *l, unsigned i)
 445 {
 446   return (LttvModule *)(l->modules->pdata[i]);
 447 }
 448
 449
 450 unsigned lttv_library_number()
 451 {
 452   return libraries->len;
 453 }
 454
 455
 456 LttvLibrary *lttv_library_get(unsigned i)
 457 {
 458   return (LttvLibrary *)(libraries->pdata[i]);
 459 }
 460
 461
 462 void lttv_library_path_add(char *name)
 463 {
 464   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Add library path %s", name);
 465   g_ptr_array_add(library_paths,(char*)g_strdup(name));
 466 }
 467
 468
 469 void lttv_library_path_remove(char *name)
 470 {
 471   guint i;
 472
 473   for(i = 0 ; i < library_paths->len ; i++) {
 474     if(g_str_equal(name, library_paths->pdata[i])) {
 475       g_free(library_paths->pdata[i]);
 476       g_ptr_array_remove_index(library_paths,i);
 477       return;
 478     }
 479   }
 480 }
 481
 482
 483 unsigned lttv_library_path_number()
 484 {
 485   return library_paths->len;
 486 }
 487
 488
 489 char *lttv_library_path_get(unsigned i)
 490 {
 491   return (char *)(library_paths->pdata[library_paths->len - i - 1]);
 492 }
 493
 494
 495 void lttv_module_register(struct _LttvModuleDescription *d)
 496 {
 497   *module_next = d;
 498   module_next = &(d->next);
 499 }
 500
 501
 502 static void init()
 503 {
 504   if(initialized) return;
 505   g_assert(destroyed);
 506
 507   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Init module.c");
 508
 509   initialized = TRUE;
 510   destroyed = FALSE;
 511   lttv_module_error = g_quark_from_string("LTTV_MODULE_ERROR");
 512   modules_by_name = g_hash_table_new(g_str_hash, g_str_equal);
 513   libraries = g_ptr_array_new();
 514   libraries_by_g_module = g_hash_table_new(g_direct_hash, g_direct_equal);
 515   library_paths = g_ptr_array_new();
 516
 517   if(builtin_chain == NULL) builtin_chain = module_chain;
 518   module_chain = builtin_chain;
 519   library_add("builtin", NULL, NULL);
 520 }
 521
 522
 523 static finish_destroy()
 524 {
 525   guint i;
 526
 527   if(initialized) return;
 528   g_assert(!destroyed);
 529
 530   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Finish destroy module.c");
 531   g_hash_table_destroy(modules_by_name);
 532   g_ptr_array_free(libraries, TRUE);
 533   g_hash_table_destroy(libraries_by_g_module);
 534   for(i = 0 ; i < library_paths->len ; i++) {
 535     g_free(library_paths->pdata[i]);
 536   }
 537   g_ptr_array_free(library_paths, TRUE);
 538   destroyed = TRUE;
 539 }
 540
 541
 542 static void destroy()
 543 {
 544   guint i, j, nb;
 545
 546   LttvLibrary *l, **locked_libraries;
 547
 548   LttvModule *m;
 549
 550   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Destroy module.c");
 551
 552   /* Unload all libraries */
 553
 554   nb = libraries->len;
 555   locked_libraries = g_new(LttvLibrary *, nb);
 556
 557   for(i = 0 ; i < nb ; i++) {
 558     l = (LttvLibrary *)(libraries->pdata[i]);
 559     locked_libraries[i] = l;
 560     library_lock_loaded(l);
 561     for(j = 0 ; j < l->modules->len ; j++) {
 562       m = (LttvModule *)(l->modules->pdata[j]);
 563       while(m->info.require_count > 0) lttv_module_release(m);
 564     }
 565     while(l->info.load_count > 0) lttv_library_unload(l);
 566   }
 567
 568   for(i = 0 ; i < nb ; i++) {
 569     l = locked_libraries[i];
 570     library_unlock_loaded(l);
 571   }
 572   g_free(locked_libraries);
 573
 574   /* The library containing module.c may be locked by our caller */
 575
 576   g_assert(libraries->len <= 1);
 577
 578   initialized = FALSE;
 579 }
 580
 581 LTTV_MODULE("module", "Modules in libraries",                         \
 582     "Load libraries, list, require and initialize contained modules", \
 583     init, destroy)
 584